Postoperative pain caused by surgery-associated tissue injury is a major concern for all the clinical practitioners. Because it affects multiple systems and induces physiological, immunological and psychological changes. Previous literature showed surgical injury induces a systemic inflammatory metabolic-endocrine response that is proportional to the severity of the surgical stress. In surgeries such as liver transplantation, the patients suffer not only from postoperative pain but also an additional oxidative stress caused by ischemia reperfusion. Previous report have proved that an adequate postoperative pain control improves the recovery and reduces the inflammatory cascade by suppression of physiological and psychological stresses. However, the effect of postoperative pain management on ischemia reperfusion injury is unclear so far. In this three year study, we plan to continue our previous study to test the following two hypothesis: (1) postoperative pain exacerbate remote organ injury caused by ischemia reperfusion, (2) the interaction of different antinociceptive modalities on ischemia reperfusion injury.